Electrical alarm switch



April 3, 1951 J. R. BROWN ELECTRICAL ALARM SWITCH Filed June 4,

ALARM vIl" Inl sa@ FIG. 2

IN VEN TOR.

Patented Apr. 3, 1951 ELECTRICAL ALARM SWITCH John Rowland Brown,

to The Reliance Ga Cleveland, Ohio, assignor uge Columnr Company Application June 4, 1949, Serial No. 97,237

3 Claims.

My invention relates to an alarm switch operated by the release of steam into the open from a steam boiler.

Many devices have been constructed wherein an electrical switch is operated when a steam Whistle in a noisy factory blows to sound an alarm located remotely in a quiet cnice. These devices have always used pistons or parts extending from the switch into a steam chamber and required packing around the parts to prevent leaking of steam. My alarm switch has a bimetal strip on the outside of the steam chamber and responsive to steam exhausting from an opening in the chamber to operate the alarm switch and therefore does not have any pistons extending into the steam chamber and thus does not require packing. I have also found it advisable to extend the bimetal strip about the whistle to prevent wind blowing the steam Iaway before it contacts the bimetal strip.

One of the objects of my invention is to construct an alarm switch which responds to steam blown into the open from an exhaust of a steam boiler or chamber housing. l

Another object of my invention is to expose a bimetal strip to the steam exhausting or blowing into the open from a steam exhaust and have that bimetal strip operate an electrical switch.

Another object of my invention is te extend a bimetal strip at least partially around a steam whistle and in the path of exhausting steam and have that bimetal strip operate an electrical switch.

Another object of my invention is to provide an alarm operating in conjunction with a steam whistle wherein steam blowing from the steam whistle engages a bimetal strip which operates an alarm switch.

Other objects and a fuller understandingr of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

Figure l is a side view of my alarm switch being used in conjunction with a steam whistle mounted on the side of a water column which is diagrammatically illustrated by the dash-dot lines.

Figure 2 is a front View of my alarm switch taken along line 2-2 of Figure 1; and

Figure 3 is a cross-sectional view cf my alarm switch taken along line 3 3 of Figure 2.

In Figure l of my drawings, I illustrate the preferred embodiment and mounting of my alarm switch I0, wherein I use a steam whistle I I as an exhaust for exhausting steam from a steam boiler or chamber, such as a water column I 2. A shield I3 supports the switch I on one side thereof with the whistle II disposed on the other side thereof. This shield prevents steam, exhausting from the whistle I I into the open or atmosphere, from coming in contact with the electrical switch I0. A temperature-responsive bimetal strip I4 extends at least partially into the path of blowing or exhausting of steam into the open and operates the electrical switch. When the bimetal strip is extended about the whistle, wind wi.l not blow the steam away from the whistle before it contacts the bimetal strip. The bimetal strip is always in the path of exhausting of the steam.

The switch I D isV an electrical switch which m-ay be purchased on the market for opening and closing circuits, such for example as the alarm circuit of Figure 1. I have found it preferable to use a micro-switch having rubber bellows I5 supporting a switch-operating plunger It. Movement of the plunger I6 operates the switch. In Figure 1 of my drawings, I have illustrated the end of a conduit I'I fastened to this switch IU and through which wires I8 may be connected to a horn or other alarm I9 located at a distance from the switch. This signal device Or alarm I9 may be positioned in a quiet oice so that a worker who would not ordinarily be able to hear the steam whistle because of factory noise, would know when the water level in the boiler had reached a dangerous point.

The Whistle I I is carried by a nipple 29 threaded into the water column I2. This nipple has valves therein operable to release steam when the water level in the water column or boiler reaches a high or a low level. When the water level falls below a predetermined point, a low iloat 2I opens the whistle valve in the nipple 20 to release steam into the whistle, thus causing it to sound an alarm. Similarly, when the water rises above a predetermined point, a highloat 22 is buoyed up, thus opening the whistle valve in the nipple 20 to blow the whistle. The structure of the nipple 2 il and the valve. therein is generally described in a prior Patent No. 1,322,598, issued November 25, 1919 to A. N. Miller et a1. I do not herein describe the details of operation of this nipple 29 and the floats 2| and 22 to cause blowing of the whistle II, since the operatQon is the same as that described in the above-mentioned patent. In understanding the operation of my invention, it should be kept in mind that blowing the whistle II exhausts steam from the boiler or water column I2 into the open or into the atmosphere.

I surface 2l. I3 with a slot 23 through which I4 extends to operably engage of the switch I.

Y fasten the bimetal strip the other side thereof.

' outwardly away from tially exposed for direct primarily temperature and atmosphere temperature, since end 3I of the bimetal strip of movement required by the free high danger point or a The shield I3 is preferably formed from sheet metal and has a flange 24 extending outwardly therefrom on one end thereof and a support flange 25 extending outwardly from the other end thereof. This support ange 25 has an opening therein through which the threaded steam whistle support extends for engaging the nipple 20. When the steam Whistle II is threadably tightened on to the nipple 28, the support flange 25 is rigidly disposed between the whistle II and thenipple 29; ported in parallel alignment with the whistle II and thus in parallel alignment with the path of exhausting or blowing of the steam into the open. When steam escapes or exhausts from a steam whistle it blows on the outside of the whistle and longitudinally thereof.

For purposes of the description, I describe the shield I3 as having a switch surface 26 on one side and a whistle surface 21 on the opposite f side. The electrical switch II] is fastened to the switch surface 26 and the whistle II is positioned next adjacent and close to the whistle I have further provided the shield the bimetal strip the plunger I6 An angle member 29 having one side thereof, preferably but not necessarily, extending at right angles to the shield I3 and longitudinally of the whistle II is fastened to the whistle surface 2'! to support the bimetal strip I4. It is understood that other suitable means may be used to I4 to the shield I3. However, I have found this angle member 29 to be the most practical. The slot 28 is disposed on one side of the shield I3 and the angle member 29 on The whistle is close to the shield and between the angle member 29 and the slot 28.

The bimetal strip I3 is preferably secured to this angle member 29 by screws 38 and extends the whistle` surface 21, around the whistle II, and through the slot 28 to operably engage with the plunger I6 of the switch Il). The bimetal strip I4 is thus somewhat U-shaped with the mounting end of one "leg secured to the shield I3 and with the free end of the other leg positioned to operate the switch lll. The surfaces of this bimetal strip I4 extend parallel to the path of blowing of steam into the open from -the whistle II and are at least parcontact with the steam. Any pressures exerted by the steam in blowing into the open will be against the edge of the bimetal strip I4 or substantially transversely of the line of movement of the switch plunger I6 and will not cause the strip to operate the switch I8. In this manner, the switch II! is operated from the difference between the steam the bimetal strip I4 is responsive to a variation of temperature.

to provide the free Illv which, operates the switch Il) with an adjustment screw 32. This adjustment screw 32 is adjustably threadable through the free end 3l to regulate the amount endy 3I to op- I have found'it advisable erate the switch II).

When the water level in the boiler reaches a low danger point, the

steam whistle II blows. Steam is thereby ex- The shield I3 is thereby suphausted into the open in a path and contacts the surfaces of the bimetal strip I4 causing the bimetal strip Ill to respond to the difference in temperature. Upon responding to the difference in temperature, the bimetal strip I4 moves the plunger I6 of the switch I0 to operate the switch I0 and thereby either open or close an electrical signal circuit, such as the circuit illustrated in Fig. 1. It is thus seen that exhausting of steam from the boiler operates my alarm switch to signal a person located at a distance from the boiler.

Although'the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope ,closest to the said path and What is claimed is:

1. An alarm switch for steam boilers having an exhaust for blowing steam into the open, said alarm switch comprising, a shield mounted next adjacent and close to the said exhaust and parallel to the path of blowing of steam into the open, said shield having an opening therein, an electrical switch mounted on the side of the shield furthest from the exhaust, and a bimetal strip of modified U-shaped construction having one end thereof secured to the shield on the side having the other end thereof extending through said opening and operably engageable with said switch, said bimetal strip having exposed surfaces parallel to and in the path of steam.

2. In an alarm system for steam boilers, a shield having a first surface and a second surface, an electrical switch supported next adjacent the first surface of said shield, a steam whistle next adjacent the second surface of said shield, and a bimetal strip of modified U-shaped construction extending close to and about said whistle, said bimetal strip having one end secured to the second surface of the shield and having the other end thereof operably engageable with said switch to operate the switch.

3. An alarm switch for steam boilers comprising, a steam whistle having an exhaust for blowing steam to atmosphere in a path encircling said j erative association with said switch.

JOHN ROWLAND BROWN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Brent Dec. 20, 1910 Wallmann Oct. 6, 1914 Colman Sept. 6, 1932 Number 

